stomach fluke and its impact on pregnancy rate in heifers

Visited a farm in County Limerick yesterday, which had a severe outbreak of stomach fluke. The maiden heifers had previously been assessed to determine stage of reproduction cycle for the purpose of synchronization. The heifers yesterday were presented for pregnancy diagnosis and the pregnancy rate was very poor. It was noted however by the farmer that there was a severe outbreak of stomach fluke which severely stressed the heifers and resulted in low pregnancy rate. Over 60% of the heifers presented were not pregnant , were anoestrus.